Glass can be produced from glass formers, which can be theorized under the random-network theory of glass as material having heavy cation--oxygen bond strengths greater than about 335 kilo Joules per mole. Typical formers are oxides such as B.sub.2 O.sub.3, SiO.sub.2, GeO.sub.2, P.sub.2 O.sub.5, As.sub.2 O.sub.5, P.sub.2 O.sub.3, As.sub.2 O.sub.3, Sb.sub.2 O.sub.3, V.sub.2 O.sub.5, Sb.sub.2 O.sub.5, Nb.sub.2 O.sub.5, and Ta.sub.2 O.sub.5. The fluoride BeF.sub.2 also qualifies. Additional components can be mixed with glass formers to provide various effects. These components include glass intermediates, having bond strengths of about 250-350 kilo-Joules/mole, and which may or may not become part of the network; and glass modifiers, having bond strengths of less than about 250 kilo Joules per mole, and which do not become part of the network. Typical modifiers are oxides of gallium, magnesium, lithium, zinc, calcium, sodium and potassium. Other formers, intermediates and modifiers are known, as illustrated in "GLASS", Kirk-Othmer Encyclopedia of Chemical Technology, vol. 12, pp 555+(1994).
One form of glass is a silicate system containing modifiers and intermediates. Such silicates have a network of silicon to oxygen to silicon bonds. Use of a modifier, such as sodium oxide, can cleave these bonds by forming a silicon to oxygen to terminal sodium linkage. Other modifiers can be used. Such modifiers can make the glass more fluid, decrease resistivity, increase thermal expansion, lower chemical durability or increase flux.
Soda-lime glass is perhaps the most ubiquitous glass product. Such soda-lime glasses involve mixtures of alkali and alkali earths. These glasses can be produced using oxides of sodium, calcium, silicon, magnesium, aluminum, barium and potassium.
Most glass is manufactured by a process in which raw materials are converted at high temperatures to a homogeneous melt that is then formed. The raw materials used are typically sand, as the source of silicon; limestone or dolomitic lime, as the source of calcium and/or magnesium; and soda ash or caustic soda, as the source of sodium. The limestone is typically a high calcium limestone (95% calcite, CaCO.sub.3), aragonite mineral, or a dolomitic limestone (mixture of dolomite, CaMg(CO.sub.3).sub.2, and calcite). The soda ash (sodium carbonate, Na.sub.2 CO.sub.3) can be a Solvay process product or mineral deposit. Typical manufacturing processes involve the batch mixing of sand, soda ash, limestone and other materials at elevated temperatures above 1000.degree. C.
There is a continued need for new processes and materials which facilitate the production of glass and which provide energy savings and increased production through-put.